A method of ranging comprises broadcasting a discovery request to a plurality of optical network units and receiving a respective discovery response from one or more of the plurality of optical network units. Each respective discovery response is transmitted as an out-of-band signal. The method also comprises approximating a respective out-of-band round trip delay to each corresponding optical network unit based on the respective discovery response; dynamically adjusting a size of a respective quiet window for each optical network unit based on the approximated out-of-band round trip delay; determining when to start the quiet window for each corresponding optical network unit based on the respective approximated out-of-band round trip delay; receiving an in-band ranging signal from the corresponding optical network unit during the respective quiet window; and determining an in-band round trip delay estimate based on the in-band ranging signal received during the respective quiet window.